Land vehicles: wheels and axles – Wheel – Hub
Reexamination Certificate
2000-02-25
2001-07-24
Stormer, Russell D. (Department: 3617)
Land vehicles: wheels and axles
Wheel
Hub
C192S064000
Reexamination Certificate
active
06264285
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bicycle transmission mechanism, more particularly to a free-wheel hub transmission mechanism for a bicycle.
2.Description of the Related Art
Referring to
FIG. 1
, a conventional free-wheel hub transmission mechanism is shown to include an axle
3
, a spoke-mounting barrel
1
rotatably mounted around the axle
3
in such a manner that a right axle portion
300
thereof projects outwardly from a right end portion
100
of the spoke-mounting barrel
1
. A sprocket mounting member
2
is sleeved around the right axle portion
300
of the axle
3
adjacent to the right end portion
100
of the spoke-mounting barrel
1
. The sprocket-mounting member
2
includes an outer shell
201
, upon which a sprocket (not shown) is adapted to be mounted, and an inner shell
203
disposed rotatably within the outer shell
201
around the right axle portion
300
by means of a ratchet mechanism. The inner shell
203
has a barrel-coupling portion
206
, which extends into and which engages threadedly an internally threaded right end portion of the spoke-mounting barrel
1
such that the spoke-mounting barrel
1
is co-rotatable with the inner shell
203
of the sprocket-mounting member
2
in a single direction.
Some of the drawbacks of the aforementioned conventional free-wheel hub transmission mechanism are as follows:
The inner shell
203
of the sprocket-mounting member
2
has a central hole of a polygonal cross section adapted to receive an operating tool for rotation of the same with respect to the spoke-mounting barrel
1
prior to insertion of the axle
3
through the sprocket-mounting member
2
and the spoke-mounting barrel
1
. It is noted that during assembly of the conventional hub transmission mechanism, a relatively large torque, as high as 2000 kgf-cm, is required to tighten the barrel-coupling portion
206
of the inner shell
203
in the internally threaded right end portion of the spoke-mounting barrel
1
.
SUMMARY OF THE INVENTION
Therefore, the object of this invention is to provide a free-wheel hub transmission mechanism which includes a sprocket mounting member provided with an inner shell of a specific configuration and a tubular locking member that requires only a small amount of torque for mounting the inner shell on a spoke-mounting barrel.
Accordingly, a free-wheel hub transmission mechanism of the present invention includes an axle with left and right axle portions, a tubular spoke mounting barrel, a sprocket mounting member, and a tubular locking member. The spoke-mounting barrel has an internally threaded right end portion and an inner wall defining an axially extending through-hole. The axle extends co-axially through the through-hole of the spoke-mounting barrel. The right axle portion projects outwardly from the right end portion of the spoke-mounting barrel. The sprocket mounting member is sleeved around the right axle portion of the axle adjacent to the right end portion of the spoke-mounting barrel, and includes an outer shell and an inner shell disposed rotatably within the outer shell around the right axle portion. The inner shell has a barrel-coupling portion, which extends into the spoke-mounting barrel and which has a central bore extending therethrough. The central bore has a small-diameter outer section, a large-diameter inner section provided with a diameter larger than that of the small-diameter outer section, and a shoulder between the outer and inner sections of the central bore in the inner shell. The locking member is disposed within the inner shell, and has an enlarged right end section that is disposed in the large-diameter inner section and that has an outer diameter greater than the diameter of the small-diameter outer section of the central bore for preventing removal of the locking member from the inner shell, and an externally threaded left end section that engages threadedly the right end portion of the spoke-mounting barrel, thereby preventing axial movement of the sprocket mounting member relative to the spoke-mounting barrel. The locking member further has two open-ended axially extending slots at a right end thereof so as to split the enlarged right end section into two parts. A device is provided for preventing relative rotation between the sprocket mounting member and the spoke-mounting barrel.
During assembly of the hub transmission mechanism of the present invention, only a relatively small torque is applied on the operating tool in order to fasten the inner shell on the internally threaded right end portion of the spoke-mounting barrel prior to insertion of the axle through the sprocket mounting member, the locking member and the spoke-mounting barrel.
REFERENCES:
patent: 4567973 (1986-02-01), Butz
patent: 5433306 (1995-07-01), Yang
patent: 5518096 (1996-05-01), Lin
patent: 5642796 (1997-07-01), Tabe
patent: 5662197 (1997-09-01), Tabe
Ladas & Parry
Stormer Russell D.
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